Maintaining stabilization of the intestinal microbiota is important in preventing bacterial diseases in cultured fish. At present, there have been no reports on the composition and functional analysis of intestinal microbiota in Yunlong Grouper (Epinephelus moara♀ × Epinephelus lanceolatus♂). In this study we analyzed and compared the intestinal microbiota composition of healthy and diseased pond-reared fish to discern the functional profile of a healthy status. The richness and diversity of the intestinal microbiota did not differ significantly between diseased and healthy fish, yet the abundance of predominant phyla like the Proteobacteria were upregulated in the diseased Yunlong Grouper. At the genus level, a significant reduction of Cetobacterium was observed in the intestinal tracts of diseased fish, as Pseudomonas became the most dominant bacterium. To compare the intestinal microorganism abundances between the two health groups of fish, we first screened the gut bacteria and discerned 4 phyla and 12 genera to designate a healthy status in Yunlong Grouper. The environmental bacterial community influenced composition of the intestinal microbiota in Yunlong Grouper, and the intestinal microbiota of diseased fish was more susceptible to the influence of the culture water. In addition, the prediction of functional genes by phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) indicated that the intestinal microbiota of Yunlong Grouper is related mainly to the terms “metabolism, environmental information processing, genetic information processing, human diseases, and cellular processing; moreover, the functions of the intestinal microbiota differed between the different health states of this fish. The overall results indicate that the occurrence of disease can affect the composition and function of the intestinal microbiota in a cultured fish.

中文翻译：

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健康和患病的云龙石斑鱼肠道菌群组成和功能的比较

保持肠道菌群的稳定对于预防养殖鱼类的细菌性疾病很重要。目前，还没有关于云龙石斑鱼（Epinephelusmoara♀ ×  Epinepheluslanceolatus♂）肠道菌群 组成和功能分析的报道。在这项研究中，我们分析并比较了健康和患病池塘饲养鱼的肠道菌群组成，以识别健康状态的功能状况。患病鱼和健康鱼之间肠道菌群的丰富度和多样性没有显着差异，但是患病的云龙石斑鱼中主要的菌群（如变形杆菌）的含量上调了。在属水平上，在患病鱼的肠道中观察到中心杆菌，如假单胞菌成为最主要的细菌。为了比较两个健康鱼群之间肠道微生物的丰度，我们首先筛选了肠道细菌并辨别了4个属和12个属，以确定云龙石斑鱼的健康状况。环境细菌群落影响了云龙石斑鱼肠道菌群的组成，病鱼的肠道菌群更容易受到养殖水的影响。此外，通过对未观察到的状态进行重建（PICRUSt）对群落进行系统发育研究来预测功能基因，结果表明，云龙石斑鱼的肠道菌群主要与“代谢，环境信息处理，遗传信息处理，人类疾病和细胞加工；而且，在这种鱼的不同健康状态下，肠道菌群的功能也有所不同。总体结果表明，疾病的发生会影响养殖鱼类肠道菌群的组成和功能。